Draft Day star Jennifer Garner knows her basic draft history, but to learn what's involved in managing the salary cap for an NFL team, which her character in the film is in charge of, she studied a real-life "capologist," specifically the Cleveland Browns' Megan Rogers, since the movie follows a fictional version of the NFL team and was filmed at the team's facility.

"I just followed her around, because she is just the coolest lady, and I copied everything," Garner said on Wednesday's Good Morning America. "I copied what she had in her hands. I copied the way she dressed. I kind of want to be her."

Garner explained that her character, and Rogers, manages business affairs and contracts for the team, monitoring what money is hitting the cap and when.

But while Garner's unlikely to leave Hollywood for a job in an NFL front office, she does have experience working with a football team. Indeed, the West Virginia native was the water girl for her high school football team her senior year, and she has a message for the players.

"If you guys don't go and see this movie this weekend, you are seriously in trouble with me," she said on the ABC morning show.

Offscreen, Garner recently joined Halle Berry to urge California to pass a law that increased penalties for harassing stars' children, which she said has "made the hugest difference in our lives but particularly in our kids' lives."

The actress also revealed that her daughter Violet also advocated for the law, writing a speech that she gave before the lawmakers and police officers who visited their house before the bill passed.

"She articulated what it meant for her that this law was going to be passed and how different she thought it would make her life, and I think everyone just forgot, 'Oh, this really is about these kids' experiences of the world,' " Garner shared, indicating that she was quite proud.

Watch Garner's full interview below, including why she makes pajamas with Ben Affleck's face on them for her kids.